Section 5 | Page 1

The color of an object depends on the light source, the wavelengths of light the object reflects and the perception of the viewer. Different light sources affect what we see. You have probably experienced how colors appear to change when viewed under different lighting conditions. For example, the tie you buy in a shop with fluorescent lighting can look different when viewed at home under incandescent light.

The greenness of the fluorescent light in the shop and the redness of the incandescent light at home can cause the object to reflect different amounts of light back to the viewer, and therefore cause the sensation of a different color.

If an apple appears red when illuminated with white light, it means the apple is absorbing green and blue wavelengths of white light and reflecting red wavelengths back to the viewer. If the same red apple is illuminated with light minus the red wavelengths, it would appear black. This is because all the wavelengths of light illuminating the apple would be absorbed and none would be reflected back to the viewer.